Regulation of phospho-2-keto-3-deoxy-heptonate aldolase (DAHP synthase) and anthranilate synthase of Pseudomonas aureofaciens.

Abstract

Phospho-2-keto-3-deoxy-heptonate aldolase (DAHP synthase) of Pseudomonas aureofaciens ATCC 15926 was inhibited by L-tyrosine. The inhibition was competitive with erythrose 4-phosphate as the varied substrate but non-competitive with respect to phosphoenolpyruvate. Anthranilate synthase was inhibited by L-tryptophan. The inhibition was competitive with respect to chorismate but non-competitive with L-glutamine or NH4+ as the varied substrate. DAHP synthase and anthranilate synthase were not repressed when aromatic amino acids were included in the growth medium. In bacteria grown in the presence of L-phenylalanine, the anthranilate synthase activity was enhanced about threefold compared with the control. Similar results were obtained with the mutant strain P. aureofaciens ACN, which produces increased amounts of pyrrolnitrin.